1. Field of the Invention
The present invention relates to a magnetic head device mounted on, for example, a magneto-optical disk apparatus and, more particularly, to a magnetic head device capable of minimizing a sway of a head body which is parallel to a surface of a recording medium, and permitting easy application of load to the head body toward the recording medium.
2. Description of the Related Art
FIG. 6 is a top plan view showing a conventional magnetic head device, and FIG. 7 is a side view of the magnetic head device of FIG. 6.
In the magnetic head device shown in FIGS. 6 and 7, a proximal end portion 1c of a load beam 1, which is a supporting member, is fixed to a carriage 2, which is a rigid member, via fixing holes 1e and 1e. A head body 3 is attached to a distal end portion 1d of the load beam 1 via a flexure. For the purpose of clarity, the flexure is not shown in FIGS. 6 and 7.
The load beam 1 is formed of a leaf spring. In the load beam 1, rails 1a and 1a, which are rigid, are formed on both sides from a vicinity of a distal end thereof to a vicinity of the proximal end portion 1c. Leaf spring portions 1b and 1b, which are free of the rails 1a and 1a and have low rigidity, are provided between terminals of the rails 1a and 1a and the proximal end portion 1c. The load beam 1 is bent by a predetermined angle xcex8 at flexed portions 1b1 and 1b1 of the leaf spring portions 1b and 1b, the distal end portion 1d of the load beam 1 being close to a recording medium 4.
The magnetic head device shown in FIGS. 6 and 7 is used to provide, for example, a vertical magnetic field for recording in a magneto-optical disk apparatus.
The recording medium 4 of a magneto-optical disk apparatus is protected by a cartridge 5 made of a plastic constituent or the like. Hence, the load beam 1 sets the head body 3 over a front surface 4a of the recording medium from above an opening 5a, extending over the cartridge 5 located between the carriage 2 and the opening 5a of the cartridge 5.
The head body 3 is subjected to an air flow generated as the recording medium 4 rotates, and lifts for a predetermined lifting distance. FIG. 8 is a side view of an enlarged portion of a neighborhood of the lifting head body 3.
The head body 3 includes a center core 3b and side cores 3c and 3c formed of a magnetic material, such as ferrite, that are installed in a cutout of a slider 3a formed of a nonmagnetic material, such as a ceramic constituent. A coil 3d is wound around the center core 3b. Bottom surfaces of the center core 3b and the side cores 3c and 3c are flush with a bottom surface of the slider 3a. A back core 3e made of a magnetic material, such as ferrite, is installed on top surfaces of the slider 3a, the center core 3b, and the side cores 3c and 3c. The head body 3 is supported by the load beam 1 via a flexure 6 joined to the back core.
A pivot 1f serving as a pivoting support point of the head body extends toward the recording medium 4 from a distal end portion 1d of the load beam 1. The pivot 1f is abutted against the top surface of the head body 3 via the flexure 6 to pivotally support the head body 3.
In the head body 3, when the coil 3d is energized, a closed magnetic path including the center core 3b, the back core 3e, and the side cores 3c and 3c is formed, and a vertical magnetic field is applied from the center core 3b to the recording medium 4. Energy of a laser beam 7 is applied to a rear surface 4b of the recording medium to record signals onto the recording medium 4 by magnetic modulation or optical modulation.
The recording medium 4 sometimes vertically teeters while rotating. The lifting distance of the head body 3 is set to a predetermined value, and the head body 3 is adapted to vertically move also. The head body 3 is able to move according to the vertical dislocation of the recording medium 4 because the load beam 1 is allowed to vertically teeter around the flexed portions 1b1 and 1b1 of the leaf spring portions 1b and 1b. 
The conventional magnetic device as shown in FIGS. 6 and 7, however, has been posing a problem in that the head body 3 is significantly dislocated in a direction parallel to the front surface 4a of the recording medium when the head body 3 moves according to the vertical teeter of the recording medium 4.
When the load beam 1 vertically teeters around the flexed portions 1b1 and 1b1, the pivot 1f, which is in contact with the top surface of the head body 3 to support the head body 3 so that it is allowed to teeter, moves along an arc A, having the flexed portion 1b1 shown in FIG. 9 as a center thereof. When the pivot 1f vertically moves by R on the arc A, a teetering distance of the pivot 1f in a direction X of FIG. 9 which is parallel to the front surface 4a of the recording medium is denoted by L.
In recent years, because of an increasing trend toward reducing a thickness of the recording medium 4, the vertical dislocation of the recording medium 4 during rotation is increasing. Accordingly, a teetering distance R of the pivot 1f in direction A of the arc and a teetering distance L in the direction parallel to the front surface 4a of the recording medium are increasing.
The teetering distance L in the direction parallel to the front surface 4a of the recording medium of the pivot 1f must be controlled to a certain range wherein the center core 3b shown in FIG. 8 stays in an area of the recording medium 4 where the center core 3b is activated by the energy of the laser beam 7. However, mainly due to a trend toward higher recording density of optical disk devices, there has been a demand for reducing a width W1 of the center core 3b, which requires the teetering distance L of the pivot 1f be further shortened.
To minimize the teetering distance L in the direction parallel to the front surface 4a of the recording medium when the teetering distance R of the pivot 1f in the circumferential direction remains unchanged, an arrangement must be made so that the pivot 1f vertically moves about an intersection A1 of a straight line that passes the flexed portion 1b1 serving as the teeter support point of the load beam 1 and is parallel to the front surface 4a of the recording medium, and the arc A.
In the conventional magnetic head device, however, the head body 3 is set on the recording medium 4 through the opening 5a of the cartridge 5, which protects the recording medium 4 as illustrated in FIGS. 6 and 7. Hence, the head body 3 is positioned below the flexed portion 1b1 of the load beam 1. Especially because the load beam 1 extends in the X-direction of FIG. 6, in which the recording medium 4 rotates, so as to set the head body 3 on the recording medium 4 as shown in FIGS. 6 and 7, a total length of the load beam 1 increases, and a height difference H between the pivot 1f and the flexed portion 1b1 of the load beam 1 increases. As a result, the teetering distance L in the direction parallel to the front surface 4a of the recording medium when the pivot If vertically moves by R on the arc A increases. Hence, it has been increasingly becoming difficult for the conventional magnetic head device to meet the demand for reducing the thickness of the recording medium 4 and the core width of the center core 3b of the head body 3.
Furthermore, as the total length of the load beam 1 increases, the load beam 1 will be more susceptible to vibrations or the like, and it will be difficult to accomplish assembly accuracy.
When the recording medium 4 is at rest, the head body 3 need to be pressed against the front surface 4a of the recording medium by a pressing force from the load beam 1. To obtain the pressing force, the leaf spring portion 1b of the load beam 1 must be bent at the predetermined angle xcex8 at the flexed portion 1b1 in the conventional magnetic head device. However, the load beam 1 is composed of a leaf spring, so that it has been difficult to accurately bend the leaf spring portion at the predetermined angle xcex8 by bending work.
Accordingly, the present invention has been made with a view toward solving the problems described above, and it is an object thereof to provide a magnetic head device which is capable of minimizing a sway of a head body in a direction parallel to a front surface of a recording medium, and permitting easy application of a pressing force for pressing the head body into contact with the front surface of the recording medium.
To this end, according to one aspect of the present invention, there is provided a magnetic head device comprising:
a carriage having a main body extending over a recording medium, and a bent portion that is bent at a distal end of the main body toward the recording medium;
an elastically deformable support member connected to the bent portion of the carriage; and
a head body which is installed to the support member directly or via another elastic member, and opposes the recording medium,
wherein a support point of connection between the bent portion of the carriage and the support member is positioned closer to the recording medium than it is to the main body of the carriage, and the head body is mounted on a free end of the support member that extends along the recording medium from the support point of connection.
In the present invention, the carriage in the main body extends over the recording medium, a bent portion that is bent toward the recording medium being provided at a distal end of the main body. In other words, a distal end of the bent portion in the carriage is dropped toward the recording medium. More specifically, in the magnetic head device in accordance with the present invention, the support member is connected to the bent portion of the carriage that is dropped toward the recording medium from the main body extending over the recording medium, rather than being fixed on a top surface of the carriage outside the recording medium. The support member is able to vertically teeters about the support point of connection with the bent portion of the carriage.
According to the present invention, the support point of connection between the bent portion of the carriage and the support member can be arbitrarily brought close to the front surface of the recording medium as long as the distal end of the bent portion of the carriage does not come in contact with the recording medium. Bringing the connection support point closely to the front surface of the recording medium makes it possible to reduce a difference in height from the front surface of the recording medium between the connection support point and a portion of the head body that is attached to the support member.
The head body vertically moves according to the vertical teeter of the recording medium during its rotation. At this time, as the difference in height from the front surface of the recording medium between the connection support point and a portion of the head body that is attached to the support member decreases, the distance of the teeter of the head main body in the direction parallel to the front surface of the recording medium when the head main body vertically moves decreases.
In other words, a magnetic head device can be provided that is able to control a teeter of the head body in the direction parallel to the front surface of the recording medium to a required range even when the vertical teeter of the recording medium increases as the recording medium becomes thinner, and even when a width of a center core of the head body is required to be reduced.
Moreover, according to the present invention, the total length of the support member can be reduced since the main body of the carriage extends onto the recording medium, and the support member is connected to the bent portion that is bent toward the recording medium from the distal end of the main body. Hence, a magnetic head device can be provided which is resistant to vibrations or the like, and permits higher assembly accuracy to be achieved.
According to the present invention, the support point of connection between the bent portion of the carriage and the support member is positioned nearer to the recording medium than it is to the main body of the carriage, and the head body is attached to the free end of the support member that extends from the connection support point to the recording medium. With this arrangement, when the head body is on the front surface of the recording medium, the distal end of the support member is pushed up by the head body thereby to allow the support member to flex in a direction away from the recording medium or flex upward, using the connection support point as the support point. The support member flexed upward presses the head body into contact with the front surface of the recording medium by a reaction. This arrangement obviates the need for machining the support member to provide it with the flexing structure, which used to be necessary in the past.
In the present invention, the bent portion constituting the carriage may be formed integrally on the main body or formed by attaching a separate member to the distal end of the main body.
The present invention is especially useful in a case where the recording medium consists of a disk housed in a cartridge having an opening.
If the recording medium is accommodated in a cartridge, the conventional magnetic head device requires that the support member extend over the cartridge to move the head body to the front surface of the recording medium. This automatically results in a higher support point of the vertical teeter of the support member.
According to the present invention, if the recording medium is the disk accommodated in the cartridge having the opening, the main body of the carriage is positioned outside the cartridge, and the bent portion of the carriage extends into the cartridge through the opening, so that the connection support point can be positioned in the cartridge.
Thus, according to the present invention, the support member can be extended from the connection support point positioned in the opening of the cartridge.
In other words, according to the present invention, a height of the connection support point can be arbitrarily set in the cartridge as long as the distal end of the bent portion of the carriage does not come in contact with the recording medium.
More specifically, according to the present invention, even when the recording medium is housed in the cartridge having the opening, the difference in height from the front surface of the recording medium between the connection support point and the portion of the head body that is attached to the support member can be reduced. Therefore, when the recording medium is vertically teetered, the teeter of the head body in a direction parallel to the front surface of the recording medium can be reduced. This arrangement makes it possible to provide a magnetic head device that permits a thinner recording medium and a narrower enter core of a head body to be achieved.
The support member is formed of an elastically deformable plate. Furthermore, the support member is fixed, for example, in a state wherein the support member is in surface-contact with the bent portion of the carriage, and bent at a surface where the support member is fixed to the bent portion and extended along the recording medium so that a corner of the bend of the support member provides the connection support point.
Preferably, the support member is formed of an elastically deformable plate, and the support member has a first bent surface opposing a recording medium and a second bent surface that is formed by bending the first bent surface in a direction along the recording medium, a head body being attached to the second bent surface directly or via another elastic member.
Forming the support member as described above makes it easy to arbitrarily adjust an elastic force of the support member at the connection support point.
Preferably, in order to minimize a teeter of the head body in the direction parallel to the front surface of the recording medium when the recording medium is vertically teetered, the head body is able to teeter about a teeter support point provided on the support member, and the connection support point and the teeter support point are positioned substantially at the same height from the surface of the recording medium when the head body is being subjected to a lifting force above the recording medium due to an air flow produced when the recording medium moves.
To remove the recording medium from an optical disk apparatus or the like, it is necessary to withdraw the support member together with the entire carriage away from the front surface of the recording medium. Preferably, the carriage is provided with a braking member for restricting a deformation of the support member toward the recording medium so as to prevent the support member from flexing toward the recording medium due to a weight of the head body attached to the distal end thereof.